Production of metal oxides, especially lead oxides



.Fan. 29 1924. 1,482,327

J. A. THIBAULT v PRODUCTIONIOF METAL oxxmas, ESPECIALLY LEAD OXIDES Filed Jan. 5, 1920 95 some mesons mm 'rnmnnar, or ets, 2: as

raonn'c'rron or METAL extras, ssrscrsnnr r. o.

Application filed January 5, 1920. fierial Ito. $49,546.

- To all whom/it may concem:

Be it known that I, JAC UES ANTOINE THIBAUUI, a citizen of the Republic of France, residing in Paris, France, have in-\ t vented a new and useful Improvement in the Production of Metal Oxides, Especially Lead Oxides, of which the following is a specification.

This invention relates to anew technical. W'method for converting metallic lead into w calcining the molten metal in contact with air in a cupel or reverb'eratory furnace or by heating the molten lead in the presence of nitrate of soda. In this latter case the oxide produced is freed from nitrite, and

so crushed by the aid of millstones in the presence of water, in which operation the metallic lead, which has not be attacked, is se arated from the oxide.

11 order'to obtain a better conversion of at the lead into lead protoxide, it has been proposed to pulverize the molten lead by impact or the like and to simultaneously cause it to be oxidized by the aid of a current of air and water-vapor.

The current of air then causes a selection to take place, by the i mpact,--between the oxidized particles and the lead which has not been converted; but even in the most improved methods, metallic lead remains in tained.

This metallic lead must be separated by lixiviation or by calcination in reverberatory furnaces, or otherwise it would interfere with the following operationwhich is necessary for converting the litharge 7 into minium. In all these known methods, in which the o ration is carried out. at a temperature hlgher than 100 C., the oxidation is efor in mechanical or other furnaces;

The red lead further is generally produced, when operating upon metallic lead, in two phases and in a succession of apparatuses.

M In the first phase, the lead is converted proportion in the litharge which is obinto lead protoxide (litharge) and in the second minium. The method according to this invention allows the conversion of the lead intoits oxygenized products without any melting gger'ation and, contrary to the usual meths can be carried out in a single apparatus; further it secures the production of oxides which are free from any metallic lead without the necessity of crushing the prodnot during the oxidizing operation or after this operation.

With them objects in view, the improved method essentially consists in oxidizing the lead in the solid state, a closed vessel and in a hot and damped atmosphere, preferably although not necessarily under pressure and in the resence of an oxidizing agent.

In t e practlcal application of the invention, the tem erature is determined in such a-manner t at, in the production of the protoxide the lead remains in the solid state and, in the production litharge does not melt.

The velocity of the converting operation depends upon the following conditions: (1) the pressure which is maintained in the apparatus, (2) the oxidizing agent and (3) the degree of moisture which is maintained in the apparatus as a consequence of the eva orization of water.

e converting operation can be efiected at atmospheric pressure but as the velocity of the operation is accelerated by the pressure which is maintained in the apparatus, it is preferably edected under pressure. This pressure is convenientl produced by aid of compressed air an through the vaporization of water which is introduced into the apparatus.

The less expensive oxidizing agent, air,

phase the. litharge is oxidized into of minium, the

may be employed, but oxygen, ozone or oxyof air, as in the usual methods, but the fact that the reaction takes place in the presence of water-vapor greatly improves the action of the oxidizing .a nt and consequently allows the shortening of the operation. .7

a commercial products.

matically an apparatus especiall In order to have the invention fully understood, it will be described hereinafter by way of examples with reference to the annexed drawings which show diagram-. adapted for its practical application, an wherein:

Fig. 1 is an elevation, partly in section, of the air and water supplying and heating device, and

Fig. 2 is a diagrammatic sectional view of the oxidizing chamber proper and its adjacent parts.

This apparatus essentially comprises an oxidizing vessel such as a rotatably mounted and tightly closed drum A arranged in a heating chamber B adapted to be externally heated either by hot air or gas coming from a furnace or in any other suitable manner. This drum is connected to a compressor 0, Fig. 1, by 9, pi which isprovided with a water distributing device D. A portion of the pipe is formed into a coil E arranged in a heating device so as to vaporize the water carried from the distributor D by the current of air. The compressed air, mixed with the water-vapor, enters the drum A through the hollow shaft F and escapes therefrom at the other end-through the shaft G.

The pressure in the drum A can be controlled by-a cock or valve H; further a suitable device I, to which the dischar dair, steam etc. from the shaft G are 1e allows the collection of the particles whichare carried away b the current of air.

Example .-A quantity of say: 3.000 kgs. of lead in form of ieces, balls, sticks or gowder, but referab y anulated, is introuced into t e drum or other suitable closed vessel adapted to continuously renew the contacts between the lead and the oxidizwithstand 'a given pressure. (Granulated lead is preferably used because this form, owing to the t number of contact oints, secures a rapi conversion into lea protoxide.)

The drum A having been set in motion grotation), a current of compressed air prouced by the compressor is charged with a small uantity of water from. the distributor This water whilst circulating with the air in the coil is vapourized and enters the drum A in which the pressure is maintained at about 4 kgs. by adjustment of the valve H.-

After 6 hours of operation, the lead is en- I tirely converted into a protoxide of a yellow ochre colour, of extra fine nature and very 6.230 kgs; of this protoxide are mg agents which are used, and which will water-vapor, at a temperature thus collected, including a small uantity of dust which is carried into the col ecting device I. I

of lead preferably of granulated form, is charged ready described.

As soon as this lead has been converted into lead protoxide, the temperature is raised to about {125 (3., which is below the melting into the drum A and treated as al- Example II.-A quantity of say 3.000 kg s.

point of. the oxlde', whilst maintaining the current of'damped air and a ressure of about 4 kilogs. After 4'hours 0 operation, the whole charge of protoxide of lead is converted into red lead having a bright red color and yielding 33 to 341% of'lead per-.

oxide.

.The product is impalpable and unctuous and need not be pulverized. 3.308 kgs. of minium (including the dust collected in the device I) are thus obtained.

The technical and i dustrial advantages of this improved method are ve important.

The handling of'the lead oxi es, which is always dangerous for the workmen, is reduced to aminimum. Further the oxidizing operation is efi'ected in a closed vessel, at temperatures which can be easily controlled,

and always below the melting points of the products which are to be oxidized. Finally this oxidizing operation takes place in a damped atmosphere which. secures amorphous products, which are impalpable and unctu'ous, having a good covering power,

of bright colors and which do not require a pulvenzing operation. The operation fur ther is effected in a relatively short time which secures a great economy of time, power and labour.

Although the invention has been described as specially ap lied to the treatment of lead, it could also ap lied usefully to other metals such as zinc, or example, in the manufacture of oxides and colors. 1

Having thus described my, invention, what I claim is:

1. The improved method for the production of metal oxides which consists in charging the solid metal in a divided state in a closed vessel, heating the said metal at a tem rature below its melting point, introducmg a current of air underpressure into the vessel together with water-vapor, agitating the metal so as to improve its contact with the air and water-vapour, simultaneously maintaining a given pressure of air and water vapour inthe vessel and finally raising the temperature above the melting point of the metal but below the melting point of an intermediary oxide. 2. The improved-met ed for the production of lead oxideswhich consists-in heating solid lead in a divided state in a closed ves sel in the presence of an-oxidizing a nt atilild' ow e neeasa'r melting point of the lead, whereby an intermediary oxide is produced, and then raising the temperature above the melting point of the metal but below the melting point of said intermediary oxide while maintaining the action of the oxidizing agent and water vapor, whereby red lead is finally produced.

3. The improved method for the production of lead oxides which consists in charging solid lead in a divided state in a closed vessel, heating at a temperature below the melting point of the lead, introducing a current of air and water vapor under pressure I into the vessel, controlling the escape of the compressed air and water-vapor from the vessel whereby the lead is subjected therein to a suitable pressure and is converted into lead protoxide, then raising the temperature above the melting point of the metal but below the melting point of the lead protoxide while maintaining the action of the current of air and water-vapor under pressure, whereby red lead is finally produced.-

In witness whereof I have signed this specification in the presence of two witnesses. 25

JACQUES ANTOINE Tl-HBAULT.

Witnesses:

PIERRE GAURICHON, EMILE LoUIs POTAY. 

